The present invention is one relating to a thermal analysis apparatus measuring how physical properties of a sample change along with a temperature. Especially, it is one relating to a differential scanning calorimeter which, when the temperature has been changed, measures a heat quantity, that the sample excessively radiates or absorbs in comparison with a reference material, on the basis of a temperature difference (differential heat) between the sample and the reference material.
The differential scanning calorimeter is an apparatus which, when the sample and the reference material (thermally stable material, e.g., alumina and the like) have been disposed while being juxtaposed and temperatures of both have been changed at a constant rate, differentially detects the heat quantity that the sample excessively radiates or absorbs in comparison with the reference material.
As to this kind of apparatus, although various ones are provided, as one of them, there is known one having a cooling mechanism which not only heats the temperature of an accommodation chamber accommodating the sample and the reference material but also cools it.
For example, there is known one having a cooling device (electric cooling device) in which a coolant is supplied to a periphery of a heating furnace which heats the sample, thereby cooling a periphery of the sample through the heating furnace (e.g., JP-B-7-65974).
Further, as other apparatus, there is also known one having a cooling device (gas cooling device) in which a very low (e.g., −196° C.) gas obtained by evaporating a liquefied nitrogen and the like is supplied into a sample chamber (accommodation chamber) accommodating the sample, thereby cooling a sample chamber inside (e.g., JP-B-7-122619).
Additionally, there is also known one in which there are used in combination a gas cooling device performing the cooling by the very low temperature gas obtained by evaporating the liquefied nitrogen and the like, and an electric cooling device performing the cooling by compressing the coolant by a compressor and adiabatically expanding it, thereby cooling a heat sink (accommodation chamber) accommodating the sample (e.g., JP-A-2005-83763).
Like this, the differential scanning calorimeter performs an analysis of the sample under various temperature conditions by freely controlling the temperature by the cooling devices of various kinds.
However, in the above conventional methods, the following problems are left.
That is, in the differential scanning calorimeter having the cooling device, a heat flow path that is a flow passage of a heat is secured by mechanically connecting the accommodation chamber, e.g., the heat sink, accommodating the sample and the cooling device. This is for efficiently heating and cooling the heat sink.
However, the heat sink and the cooling device are not made by a material of completely the same quality, but generally are respectively made by utilizing materials of different qualities. In other words, the heat flow path is formed by mechanically connecting metals of different kinds to each other. Therefore, when analyzing the sample, if the heating and the cooling are repeatedly performed, a distortion, a deviation and the like have occurred in a joint face due to a difference in thermal expansion coefficient. As a result, a flow of the heat changes midway, so that there has existed a possibility that it is impossible to accurately perform the analysis of the sample. Further, since the distortion and the deviation change every moment in compliance with conditions at that time, a reproducibility is bad, and it has been impossible to collect a measurement result and the like.
The present invention is one having been made in view of the circumstances like this, and its object is to provide a differential scanning calorimeter in which, even if the heating or the cooling has been repeatedly performed, it is possible to maintain a stable heat flow path, and which can highly precisely perform a measurement of the sample to be measured.